The present invention relates to a self-aligning resilient clutch release bearing for disc clutches and, more particularly, for diaphragm clutches, said release bearing comprising an anti-friction bearing, for example a ball bearing, one of the races of which is provided with a resilient sleeve enabling axial sliding and also permitting radial and angular movement of the other race in contact with the diaphragm for its alignment during each disengagement of the clutch.
It is known that this type of clutch release bearing comprising a ball bearing or the like should preferably be provided with a resilient device permitting a certain movement of the release bearing in relation to the shaft of the gear box of the vehicle, or in relation to the guide tube on which the release bearing moves. It is in fact known that one of the two races of the ball bearing of such a release bearing which transmits the clutch disengagement stress, comes into direct supporting contact with the diaphragm or remains in continuous contact with the latter, while the other race receives the thrust of the clutch disengagement fork. The race coming into contact, or remaining in contact, with the diaphragm, for example the inner race of the bearing, has a substantially toric supporting surface, the release bearing being neither exactly centered on the shaft of the gear box nor exactly aligned in relation to the axis of rotation of the diaphragm. Besides, the geometric axis of the diaphragm of the clutch, its axis of rotation, and the axis of the shaft of the gear box or of the tube guide do not always coincide exactly, which makes it all the more necessary to provide a possibility for the release bearing to move at the moment of each clutch disengagement.
To cure these disadvantages, an antifriction lining may be provided either on the race or on the diaphragm or on the two members in mutual contact, so as to reduce friction and wear and tear of said members which are off-center in relation to each other during each clutch disengagement operation.
It is also known to provide clutch release bearings comprising means for insuring their automatic alignment during each clutch release. In release bearings of this type, elastic elements of various forms are interposed between one of the races of the ball bearing and the tube guide, or between the latter and a sliding socket which moves in relation to the tube guide or in relation to the shaft of the gear box. However, until now the structure of the elastic elements thus interposed has not made it possible to obtain correct functioning, that is, an automatic alignment during each clutch disengagement operation. It is in fact essential that the structure of these elastic elements be such that the latter be able to move radially and to pivot under the action of a relatively weak force deriving from the reaction of the bearing of the release bearing on the clutch diaphragm. Further, it is also necessary that the flexibility of said elastic elements be not too great, so as to insure correct functioning of the device and correct retention of the release bearing in engaged clutch position.
In U.S. Pat. No. 3,631,954 a clutch release bearing has already been provided in which a sliding socket integral with the inner race of the ball bearing moves on the tube guide through the intermediary of one or several toric joints of resilient material. Other structures of resilient elements are, for example, of the type shown in U.S. Pat. No. 3,805,934 where the interior ball race is integral with a cylindrical sleeve of resilient material, said race having thin walls obtained by stamping from a metal sheet or a tube. In relation to the preceding embodiment, this latter embodiment has the advantage of greater simplicity of manufacture, taking into account the thin-walled structure of the interior race of the bearing and the possibility of molding the resilient sleeve onto the interior race. It is, however, noted that the results obtained from such a structure are unsatisfactory.
Clutch release bearings are also known in which a resilient element with discontinuous contact is interposed between one of the races of the ball bearing and a socket capable of sliding in relation to the tube guide. A U.S. Pat. No. 3,625,327 shows such an arrangement in which the sliding socket is connected to a ball bearing with massive races through the intermediary of a plurality of individual radial nipples working at the compression. Such a structure is complex and does not permit correct functioning. In French Pat. No. 73 43651 and U.S. Pat. No. 3,921,775, one again finds a substantially analogous device in which a ring of plastic material having projections oriented obliquely in relation to the axis and interposed between one of the races of the ball bearing and a sliding socket.
In this last embodiment, the massive ring of the bearing is further in frictional contact with a radial surface of the sliding socket, which hinders considerably the desired self-alignment. Further, this arrangement has the same complexity as the preceding one.
The object of the present invention is to cure these disadvantages and to provide a clutch release bearing which insures automatic alignment at each clutch disengagement operation in a simple manner, thanks to an easily manufactured structure enabling convenient adjustment of the flexibility of the unit. The present invention also aims at a resiliently self-aligning clutch release bearing comprising a thin-walled ball bearing provided with a resiliently centering sleeve of particular structure having at once the rigidity and the flexibility necessary for correct functioning and repeated by the bearing during functioning of the clutch engagement of the vehicle.